This invention relates to the field of electrical connectors. More particularly, this invention is directed to a method and an apparatus for making electrical connection to an electrical element on a movable member, such as to the coil of an actuator, for example.
In developing the fluid mount described and claimed in copending U.S. patent application Ser. No. 07/776,118 filed Oct. 15, 1991, entitled "Fluid Mount with Active Vibration Control," which is hereby incorporated by reference, one of the most significant problems was in making reliable electrical contact with the reciprocating voice coil on actuator 36. Conventional connections proved unworkable. Such a connection utilized a wire which was required to flex repeatedly at a high velocity and frequency. Any wire that was used to effect connection between a relatively stationary power source and the relatively movable actuator coil would quickly fatigue and break.
In choosing a current path, it was of primary importance in the design to use wire connections only between relatively stationary members and to utilize an alternate connector capable of repeated flexing between relatively moving members. By doing so, the fatigue problems associated with repeated flexing of the connecting wire can be eliminated.
The objective of obtaining a reliable electrical connection to a reciprocating member is accomplished by modifying the electrical flow path to permit helical centering springs to form the connecting element in the moving segment of the system. Wires are then used to connect elements that experience little or no relative movement so no flexing of potentially brittle wires results. The centering springs, which are used to return the piston of an actuator to its neutral position, are contacted on each end by a washer made of conductive (e.g., brass, copper) material.
An electrical connector that is mounted upon a relatively stationary structure is hard-wired to a first washer that experiences no motion relative to that stationary structure. Electrical current is transmitted from an electrical supply, through the connector, via the hard-wired connection to the first washer, then axially through the helical centering spring to the second washer. This second washer is hard-wired to the coil of the actuator. Again, there is no relative motion between the second washer and the coil, since both move together.
In a first single-coil actuator embodiment, the current's returnflow path extends from a third washer hard-wired to the opposite end of the actuator's coil, through a bolt of conductive (e.g., brass) material, through a fourth washer, into a second opposing centering spring, into a fifth washer that is hard-wired back to the connector. As was the case with the first two hard-wired connections, these latter two are between relatively immovable components, the coil and third washer being commonly associated with the movable portion of the actuator and the fifth washer and the actuator both being associated with the relatively stationary support structure.
In a second double-coil actuator embodiment, which has a coil at each end of the actuator, each of the centering-spring means is comprised of first and second coaxial, substantially co-extensive helical springs. A first tabbed washer affords a first hard-wired connection to the power source's electrical connection. The current travels axially through the inner helical spring to a second tabbed washer which is hard-wired to a first end of the actuator's coil, the opposite end of the coil being hard-wired to a fourth tabbed washer which is adjacent to the second washer. The outer helical spring serves as a conductor in the return current flow path to a third tabbed washer which is adjacent the first washer and is hard-wired back to the connector. A first spring retainer maintains the first and third washers in non-conducting, spaced relation and a second spring retainer performs the same function for the second and fourth washers. The coil on the opposite end of the actuator utilizes the outer coil as the current input path so as to be reverse wired so the series input current to both actuators drives them in phase.
Various other features, advantages and characteristics will become apparent after a reading of the following detailed description.